The new prefix length will be 32 10 22 So new Subnet mask is 2552552520 TDC 413

# The new prefix length will be 32 10 22 so new subnet

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The new prefix length will be 32 – 10 = / 22 . So, new Subnet mask is 255.255.252.0 . TDC 413 72 Rami Ghannam, DePaul University JoyCo Example Subnet sizes must be powers of 2. The smallest power of 2 that is greater than 1000 is 2 10 = 1024. This would give them 1024 – 2 = 1022 valid host addresses in each subnet. Thus, each IP address needs 10 Host bits. The new prefix length will be 32 – 10 = / 22 . So, new Subnet mask is 255.255.252.0 . The difference between old prefix length (16) and new prefix length (22) is 22-16 = 6 , so 6 bits are borrowed: Number of new subnets = 2 6 = 64 subnets TDC 413 72 Rami Ghannam, DePaul University JoyCo Example Subnet sizes must be powers of 2. The smallest power of 2 that is greater than 1000 is 2 10 = 1024. This would give them 1024 – 2 = 1022 valid host addresses in each subnet. Thus, each IP address needs 10 Host bits. The new prefix length will be 32 – 10 = / 22 . So, new Subnet mask is 255.255.252.0 . The difference between old prefix length (16) and new prefix length (22) is 22-16 = 6 , so 6 bits are borrowed: Number of new subnets = 2 6 = 64 subnets We also could have figured this as 65,536 / 1024 = 64 TDC 413 72 Rami Ghannam, DePaul University Calculating JoyCo Subnets First Subnet ID will be the original network address with the new prefix length. First Subnet ID is 130.88.0.0 / 22 New Subnet Mask = 255.255.252.0 TDC 413 73 Rami Ghannam, DePaul University Calculating JoyCo Subnets First Subnet ID will be the original network address with the new prefix length. First Subnet ID is 130.88.0.0 / 22 New Subnet Mask = 255.255.252.0 Two ways to calculate other subnet IDs: Start with first subnet ID and add 1024 IP addresses to it. This will increase value in 3 rd byte by 1024 / 256 = 4 . TDC 413 73 Rami Ghannam, DePaul University Calculating JoyCo Subnets First Subnet ID will be the original network address with the new prefix length. First Subnet ID is 130.88.0.0 / 22 New Subnet Mask = 255.255.252.0 Two ways to calculate other subnet IDs: Start with first subnet ID and add 1024 IP addresses to it. This will increase value in 3 rd byte by 1024 / 256 = 4 . Magic number = 4 TDC 413 73 Rami Ghannam, DePaul University Calculating JoyCo Subnets First Subnet ID will be the original network address with the new prefix length. First Subnet ID is 130.88.0.0 / 22 New Subnet Mask = 255.255.252.0 Two ways to calculate other subnet IDs: Start with first subnet ID and add 1024 IP addresses to it. This will increase value in 3 rd byte by 1024 / 256 = 4 . magic number = 4 The “magic number” for each byte determines how much that byte changes between successive network IDs. TDC 413 73 Rami Ghannam, DePaul University Calculating JoyCo Subnets First Subnet ID will be the original network address with the new prefix length. First Subnet ID is 130.88.0.0 / 22 New Subnet Mask = 255.255.252.0 Two ways to calculate other subnet IDs: Start with first subnet ID and add 1024 IP addresses to it. This will increase value in 3 rd byte by 1024 / 256 = 4 .  • • • 